Finally got the Omni 546-C working like it would have when it came out of the
factory.
Replaced the new drivers (that had trouble getting a low bias) with the ones I
took out
and bias adjusted FB. The new finals (MRF 454, MACOM) are working like a charm
with
more output on the highest bands. Their bias adjusted without a hitch.
Checked the keying shape and this is real nice now, no leading spikes. I blame
the keyer
sending a dit on power up and when the rig is powered an RF signal is being
generated
before all circuits are fully initialised. There was the wrong value for a
capacitor in the
keying control circuit in the transceiver which resulted in a leading spike and
these two
items hastened the demise of the MRF 458 finals.
Put a push button with relay in the keyer so it drops out the power connection
from the
keyer and hence when switching on the rig the keyer is not triggering the TX
into
producing an RF signal.
Had some fun adjusting the carier oscillator frequencies, this was off a bit.
(Had already
been told in some QSO's that I was off frequency and the tone of the hiss was
not
the same on normal and reversed SSB.) Looks the handling of the board was enough
to upset the trimmer capacitors.
I had intended to replace the heatsink with one that has the fins vertical
oriented (and
hence increasing the cooling capacity) and had it already drilled and ready to
go in.
However it just did not look "the part" and I put the original heatsink back
on. The
rig is now all original for two deviations: using a 600 Hz Inrad CW filter and
the narrow
audio setting is now using three stahes instead of the four stages. This has
made the
narrow audio setting a lot more pleasant.
Thanks for everyone who helped with advice on rebuilding this .
Thumbs up to TenTec service who gave great advice and were very patiently
answering
my constant stream of questions.
One project completed now onto finishing the 228 ATU redesign / rebuild.
73
Marinus, ZL2ML
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